根据方法参数更改对象的类型

Question

So once again, sorry this questian might be answered/asked a lot allready, but I'm not really sure what i am searching for

I'm currently making a mod for a game and need to register custom items i created. I created custom classes for every type of item which contain various variables I need to access. The problem is, the class(es) they all inherit from does not have these variables/data.

My initial attempt was something like this (pseudo code'ish)

public void addItem(Item itemc)
{
   Object item = null;
     if (itemc.getClass().equals(ItemTool))
          item = (ItemTool) itemc;
      if (itemc.getClass().equals(ItemFood))
          item = (ItemFood) itemc;
        .......etc..........

    registerItem(item,item.name);
    registerItemRenderer(item,item.meta,item.model);
}

But that doesn't work and i get an error saying item (treated as an Object as initialized) does not have these members.

Right now i just overloaded the method addItem to accept every custom item class i made (over 10 atm), but thats not really what i want.

Is there a way to change the type of an Object to whatever class i will pass as argument and then work with it?

Answer 1

You could move the extraction of item.name into the if :

Object item = null;
Object itemName = null;

if (itemc.getClass().equals(ItemTool)) {
    item = (ItemTool) itemc;
    itemName = item.name;
} else {
    if (itemc.getClass().equals(ItemFood)) {
        item = (ItemFood) itemc;
        itemName = item.name;
    }
}

registerItem(item, itemName);

but it would be far more OO-like to create an Interface for Item to include a getName -method which every Item implements and your method does not have to know which type your item is to obtain the name:

public void addItem(Item item) {
    registerItem(item, item.getName());
}